|Leathers, Timothy - Tim|
Submitted to: Letters in Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/31/2008
Publication Date: 1/23/2009
Citation: Liu, S., Bischoff, K.M., Hughes, S.R., Leathers, T.D., Price, N.P., Qureshi, N., Rich, J.O. 2009. Conversion of biomass hydrolysates and other substrates to ethanol and other chemicals by Lactobacillus buchneri. Letters of Applied Microbiology. 48(3):337-342. Interpretive Summary: New and improved biocatalysts are needed to convert biomass into valuable fuels and chemicals. A novel lactic acid bacterium was isolated as a contaminant of a fuel ethanol production facility. Unlike conventional yeast, this organism uses a mixture of five-carbon and six-carbon sugars commonly found in agricultural residues and other lignocellulosic biomass. In this paper, the pretreated biomass hydrolysates were converted into ethanol, lactate, and acetate by this microbe. Results will be valuable to researchers developing new biocatalysts for biomass-based biorefinery platforms.
Technical Abstract: A Lactobacillus buchneri strain NRRL B-30929 can convert xylose and glucose into ethanol and chemicals. In this paper, L. buchneri NRRL B-30929 was initially compared with the type strains L. buchneri NRRL 1837 and DSM 5987 for growth and fermentation using single substrate derived from plant materials. The survey of 14 carbohydrates suggested each strain showed preferred growth with a particular substrate, for most cases, the mixed acid fermentation was observed; the only exception was uridine which yielded lactate, acetate, and uracil. Interestingly, only NRRL B-30929 is capable of utilizing cellobiose, a desired trait in a potential biocatalyst for biomass conversion. The B-30929 strain was then examined for fermenting naturally available mixed substrates, including corn stover and wheat straw hydrolysates. Flask fermentation indicated that the B-30929 strain can use all the sugars released from pretreated hydrolysates, and producing 1.98 to 2.35 g L**-1 ethanol from diluted corn stover hydrolysates and 2.92 to 3.01 g L**-1 ethanol from diluted wheat straw hydrolysates when supplemented with either 0.25 x MRS plus 1% corn steep liquor or 0.5 x MRS. These results are valuable for future research in engineering L. buchneri NRRL B-30929 for fermentative production of ethanol and chemicals from biomass.